The actions of insulin begin with insulin receptor and culminate in changes in the phosphorylation state of a number of downstream targets including phosphatidylinositol 3-OH kinase (PI3-kinase). Activation of PI3-kinase is central to insulin-stimulated phosphorylation in fat cells. In adipocytes, PI3 or the products of PI3 reaction are involved in activation of protein kinase B (PKB), glycogen synthase and phosphorylation of transitional regulators, 4E-BP1, p70s6k and mTOR protein (mammalian target of rapamycin). The kinase activity of mTOR functions in nutrient sensing pathway that maintains a proper balance of aa availability, protein synthesis and cell growth. Most importantly, mTOR controls the phosphorylation of a newly discovered protein Lipin-1, required for normal adipose tissue development and metabolism. Lipin defines a family of nuclear proteins containing at least three members in human and mouse: Lipin-1; Lipin-2 and Lipin-3. All Lipin members contain a nuclear signal seq, a highly conserved amino- (NLIP) and a carboxy-terminal (CLIP) domains.

Lipin-1: The human and mouse LPIN-1 genes have been mapped at chromosomes 2p21 and 12, respectively. A region (POMC) on this same chromosome also encodes pro-opiomelanocortin, a locus linked to total adiposity and the levels of plasma protein Leptin. The mouse Lipin-1 is a 140 kDa (891 aa) protein with many potential phosphorylated sites. The overall aa seq of mouse Lipin-1 is over 46 and 49% identical to mouse Lipin-2 and Lipin-3, respectively. The seqs of human and mouse Lipin-1 are over 88% identical. Lpin-1 mRNA is prominently expressed in adipose tissue, skeletal muscle and testis with lower expression in kidney, lung, brain and liver. A Gly84Arg mutation in Lipin-1 alters the protein's subcellular localization from nuclear to cytoplasmic and impairs its activity. The mutation in Lpin-1 gene leads to Lipin-1 deficiency which results in the development of immature adipocytes in fatty liver dystrophy (fld) phenotype in mice and in a group of rare human diseases called lipodystrophy. These phenotypes are characterized by a triglyceride-filled fatty liver, loss of body fat, hypertrigyceridemia, glucose intolerance, insulin resistance, increased susceptibility to atherosclerosis, reduced fertility, reduced plasma Leptin and a progressive neuropathy affecting peripheral nerves in adulthood.

Lipin-2: The human and mouse LPIN-2 genes have been mapped at chromosomes 18p and 17, respectively. The Lipin-2 seqs from mouse and human are ~90% identical. The overall aa seq of mouse Lipin-2 (891aa) is ~48% identical to mouse Lipin-1(891aa) and Lipin-3 (848aa).

Lipin-3: The human (LPIN3) and mouse Lipin3 genes have been mapped at chromosomes 20q and 2, respectively. The overall aa seq of mouse Lipin-3 (848aa) is 46% and 48% identical to mouse Lipin-1 (891aa, 140 kDa) and Lipin-2 ((891aa), respectively.

ADI has produced highly specific rabbit polyclonal antibodies to Lipin-1, Lipin-2, Lipin-3 which should aid the studies related to adipose tissue development in the context of obesity, fatty liver dystrophy, lipodystrophy, insulin resistance and Type 2 diabetes.
 

m=mouse; r=rat; h=human; b=bovine; c=chicken; d=dog; ~CT or ~NT=near C or N-terminus. EC=Extracellular; CL=Cytoplasmic loop;

* Expected antibody crossreactivity information is mostly based upon high (>70%) sequence conservation of antigenic/control peptides in various species. When antibody crossreactivity has actually been experimentally confirmed in various species, it will be mentioned in the appropriate data sheets.

"Affinity pure" IgG may be more suitable for immunohistochemical (IHC) applications and to reduce background in most immunological applications including ELISA and Western.
"Control peptides" can not be used for Western as they are very short peptides. They are intended for ELISA or antibody blocking studies to establish antibody specificity.
Western blot +ve protein controls, where available, are semi-pure, pure or recombinant proteins that are formulated in SDS-PAGE sample buffer. They are recommended to be used for Western (load 10 ul/lane) for visualization with antibodies.